Correlation of Scattering Loss, Sidewall Roughness and Waveguide Width in Silicon-on-Insulator (SOI) Ridge Waveguides

We use star couplers to measure the relative scattering losses of silicon-on-insulator (SOI) ridge waveguides of various widths over the range of 1.75 to 0.2 $mu$m in a single measurement. The scattering loss data obtained for waveguides fabricated by different photolithography and e-beam base processes correlate well with the measured root-mean-square roughness of the waveguide sidewalls obtained using SEM image analysis, and are in qualitative agreement with the prediction of simple scattering loss theory.      

Silicon Waveguide Sidewall Smoothing by KrF Excimer Laser Reformation

A novel laser-reformation technique is presented for sidewall smoothing of silicon waveguides. A KrF excimer laser is used to melt and reform the sidewalls to reduce the surface roughness. Atomic-force-microscopy measurement shows that the root-mean-square (rms) roughness is reduced from 14 to 0.24 nm. The calculated scattering loss is reduced to 0.033 dB/cm. The waveguide profile after laser illumination at an incident angle of 75deg transforms to a shape of arch. The crystal quality of laser-illuminated silicon wafer characterized by microwave reflection photoconductance-decay carrier lifetimes shows 94% less damage than the furnace-treated wafer.     

AlGaAs湿法氧化的热稳定性研究

文中针对AlGaAs湿法氧化后器件热稳定性变差,导致性能下降的问题进行了研究。对不同氧化条件下样品的热稳定性进行了比较,证明采用降低炉温、延长氧化时间以及经过预加热处理等方法可以有效提高器件的热稳定性。利用拉曼谱分析了AlGaAs湿法氧化技术中影响热稳定性的因素,认为器件的热稳定性在一定程度上取决于湿法氧化生成物中挥发性产物含量的多少。     

Loss Reduction of Waveguide Crossings by Wavefront Matching Method and Their Application to Integrated Optical Circuits

This paper describes a waveguide crossing design that uses the wavefront matching (WFM) method. The WFM method enables us to design waveguide crossings with lower loss than simple crossings composed of two straight waveguides, without any crosstalk degradation. We report the procedure for designing waveguide crossings based on the WFM method and some experimental results. For experimental confirmation, we made a waveguide crossing test circuit using silica-based planar lightwave circuit (PLC) technology. By comparing the results obtained with samples constructed with different $Delta$ waveguides, we show that our design method is very efficient for higher $Delta$ waveguides suitable for high-density integration. In addition, we describe an example application of our designed crossings to an integrated PLC device, namely a wavelength multiplexer with a variable optical attenuator. We show that waveguide crossings designed by the WFM method are useful for improving the loss characteristic of highly integrated PLC devices.      

热氧化方法改善硅干法刻蚀波导的表面粗糙度

提出了一种热氧化的方法来改善干法刻蚀硅波导的表面质量.通过Suprem二维工艺模拟程序对氧化过程的物理模型进行了分析.用实验证实了该方法的可行性并与模拟结果进行了比较.实验中将硅波导的表面粗糙度由65.4nm降低到了8.8nm.另外讨论了分次氧化方法的利弊     

热氧化磁控溅射金属锌膜制备ZnO纳米棒

利用射频磁控溅射技术在Si(111)衬底上制备金属锌膜 ,在空气中退火热氧化合成了一维ZnO纳米棒。用X射线衍射 (XRD) ,扫描电子显微镜 (SEM) ,透射电子显微镜 (TEM)和光致发光谱 (PL)对样品进行了结构、形貌及光学特性分析。结果表明 :ZnO纳米棒为六方纤锌矿结构单晶相 ,直径在 30～ 6 0nm左右 ,其长度可达5～ 8μm左右。在 2 80nm波长光激发下 ,有很强的 372nm带边紫外光发射和较微弱的 5 16nm深能级绿光发射 ,说明合成的单晶ZnO纳米棒的质量较高     

Thermal Characteriztion of 1.3 μm InAsP／InGaAsP Ridge Waveguide MQW Laser Based on Spectroscopy Method

An experimental way to analyze the thermal characteriztion of semiconductor lasers based on spectroscopy method under pulse driving conditions has been developed,By using this way the thermal characteristicss of strain compensated 1.3 μm InAsP/InGaAsP ridge waveguide MQW laser diodes have been investigated.Results shovw that by measuring and analyzing the lasing spectra under appropriate driving parameters and temperature ranges,the thermal resistance of the laser diodes could be deduced easily,A higer thermal resistance of 640 K/W has been measured on a narrow ridge laser chip without soldering.Other thermal and spectral properties of the laser have also been measured and discussed.     

ICP刻蚀参数对SOI脊形波导侧壁粗糙度的影响

研究了以C4F8/SF6/O2为刻蚀气体,利用ICP刻蚀技术制作SOI脊形光波导过程中,刻蚀参数与侧壁粗糙度的关系.实验结果表明偏压、气体比例、压强是影响侧壁粗糙度的关键参数,在低偏压、低C4F8/SF6比和较高压强下更容易获得低粗糙度的侧壁.通过优化刻蚀参数,获得了侧壁粗糙度和传输损耗相对较低的SOI脊形波导.     

The Solution of Waveguide Scattering Problems by Application of an Extended Huygens Formulation

The implementation of a recent new hybrid integral-equation/vector finite-element method formulation applicable to inhomogeneous obstacle scattering in hollow waveguide, requiring discretization just of the obstacle, is presented. The integral equation links the given incident modes with the discontinuity-surface electric and magnetic fields. The finite-element equation is expressed in terms of the entire magnetic and surface electric field of the obstacle. Compatible vector finite-element basis function expansions are inserted, resulting in a pair of matrix equations soluble for the unknown electric and magnetic basis coefficients. Corresponding two-port scattering parameters are further derived. Test cases of posts in the$ TE_10$waveguide, with details of the matrix constructions, are described. Numerical results verified against an established commercial code are given. The ability to model inhomogeneous, lossy, and multiple scatterers is demonstrated.     

Variational Bound Principle for Scattering of Electromagnetic Waves by Obstacles in a Waveguide

A formulation is presented for the determination of variational bounds on the even and odd phase shifts that characterize the scattering of electromagnetic waves by symmetric dielectric obtacles in waveguides. The formulation is an extension of a technique recently developed in quantum mechanical scattering theory for the determination of variations bounds on partial-wave phase shifts for scattering by systems with internal degrees of freedom. As opposed to the usual variational principles which give values that may be below or above the true values, the formalism presented here gives results that are variational and represent rigorous bounds on the true values. The formulation is presented for a more general case, but for simplicity the method is applied to scattering from dielectric obstacles in a rectangular waveguide in which only the TE/sub 10/ mode is propagated. The method involves the use of a trial function orthogonal to the lowest mode with variational parameters and the introduction of a Green's function for a simplified problem in which the higher modes cannot be excited. Calculated values are presented for the phase shifts for the true problem and also for the series and shunt reactance of the equivalent network. The principle can be generalized to multimode waveguide problems.     

氦离子注入形成980nm脊型波导激光器腔面非注入区的研究

报道了氦离子注入技术在提高980nm半导体激光器灾变性光学损伤(catastrophic optical damage,COD)阈值上的应用.p-GaAs材料经氦离子注入后可以获得高的电阻率.在距离腔面25μm的区域内进行氦离子注入,由此形成腔面附近的电流非注入区.腔面附近非注入区减少了腔面载流子的注入,因此减少了非辐射复合的发生,提高了激光器的灾变性光学损伤阈值.应用氦离子注入形成腔面非注入区的管芯的平均最大功率达到440.5mW,没有发生COD现象.而应用常规工艺制作的管芯的平均COD阈值功率为407.5mW.同常规工艺相比,应用氦离子注入形成腔面非注入区技术使管芯的最大输出功率提高了8%.     

氦离子注入形成980nm脊型波导激光器腔面非注入区的研究

报道了氦离子注入技术在提高 980nm半导体激光器灾变性光学损伤 (catastrophicopticaldamage,COD)阈值上的应用 .p GaAs材料经氦离子注入后可以获得高的电阻率 .在距离腔面 2 5 μm的区域内进行氦离子注入 ,由此形成腔面附近的电流非注入区 .腔面附近非注入区减少了腔面载流子的注入 ,因此减少了非辐射复合的发生 ,提高了激光器的灾变性光学损伤阈值 .应用氦离子注入形成腔面非注入区的管芯的平均最大功率达到 44 0 5mW ,没有发生COD现象 .而应用常规工艺制作的管芯的平均COD阈值功率为 40 7 5mW .同常规工艺相比 ,应用氦离子注入形成腔面非注入区技术     

最佳端焦耦合法测量交叉光波导损耗特性

本文利用最佳端焦耦合法对交叉光波导的损耗特性进行了测量和研究，绘制了波导损耗随交叉次数和交叉角的变化曲线。测量结果与预期特性相吻合。     

热氧化法制备的ZnO薄膜的光致发光特性研究

在空气中利用热氧化方法分别在P型硅、高阻硅、陶瓷以及N型硅衬底上制备了氧化锌(ZnO)薄膜.同时在氧气中、P型硅衬底上氧化制备少量氧化锌薄膜加以比较.氧化时间固定为1 h,氧化温度300℃～800℃.采用X射线衍射(XRD)以及光致发光(PL)光谱研究比较薄膜的结构和PL特性.发现在氧气中氧化样品质量明显好于在空气中氧化的样品.氧气中300℃氧化时有最窄的半高宽和最大的晶粒尺寸.在高阻硅材料衬底上制备的ZnO薄膜表现出较好的紫外发射带,而在陶瓷材料上表现出较好的绿色发射带.而N型材料也是较好的紫外发射材料,P型材料在低温下表现出较好的发光特性.     

Scattering of Guided Modes Caused by an Arbitrarily Shaped Broken End in a Dielectric Slab Waveguide

Electromagnetic scattering of guided modes in a dielectric slab waveguide caused by an arbitrarily shaped broken end is analyzed theoretically by using the integral equation method. By solving the integral equations iteratively, the tangential components of the electric and magnetic fields on the broken end surface are determined, from which the reflected mode power, the radiation wave power and field patterns, and the total scattered power are obtained. Numerical results are presented for the plane-perpendicular, plane-tilted, and arc-shaped end surfaces. Both TE and TM modes are assumed as an incident wave.     

各向异性介质填充波导散射特性的三维54参量边缘元分析

本文将54参量边缘元和"边界行进"及Galerkin法相结合,分析了各向异性介质填充波导的散射特性.该方法有效地提高了计算精度和效率,明显地降低了对内存的需求,并消除了伪解.文中给出的计算实例,很好地证实了本文方法的这些优点.     

热退火γ-Al2O3/Si异质结构薄膜质量改进

采用高真空MOCVD外延技术,利用TMA(Al(CH3)3)和O2作为反应源,在Si(100)衬底上外延生长γ-Al2O3绝缘膜形成γ-Al2O3/Si异质结构材料.同时,引入外延后退火工艺以便改善γ-Al2O3薄膜的晶体质量及电学性能.测试结果表明,通过在O2常压下的退火工艺可以有效地消除γ-Al2O3外延层的残余热应力及孪晶缺陷,改善外延层的晶体质量,同时可以提高MOS电容的抗击穿能力,降低漏电电流.     

Analysis of Electromagnetic Waves Scattering by a Finite Size Dielectric and Metal Cylinder in a Rectangular Waveguide

The paper presents a rigorous solution of the scattering problem by a circular dielectric and perfectly conducting cylinders of any radius and any height in the rectangular waveguide oriented perpendicularly to a wall. The method is based on the representation of fields in waveguide and dielectric medium by cylindrical eigenfunctions and application of boundary conditions on surfaces of the cylinder to evaluate the fields inside and outside the cylinder. The reflection and transmission coefficients are expressed through the fields. As an example the reflection and transmission coefficients versus frequency for various dielectric and metallic cylinders are computed. The comparison of numerical with experimental data is presented.     

热退火γ-Al2O3/Si异质结构薄膜质量改进

采用高真空MOCVD外延技术,利用TMA(Al(CH3)3)和O2作为反应源,在Si(100)衬底上外延生长γ-Al2O3绝缘膜形成γ-Al2O3/Si异质结构材料.同时,引入外延后退火工艺以便改善γ-Al2O3薄膜的晶体质量及电学性能.测试结果表明,通过在O2常压下的退火工艺可以有效地消除γ-Al2O3外延层的残余热应力及孪晶缺陷,改善外延层的晶体质量,同时可以提高MOS电容的抗击穿能力,降低漏电电流.